Proper-motion diagram for the CNC region. The grey dots show all Gaia EDR3 objects in a 4.75° ×3° box centered around the J2000 celestial coordinates RA = 10^h43^m, Dec = −59° 20′. The blue dots show the proper motions of the X-ray-selected objects of the CCCP, NGC 3324, and NGC 3293. The green and red circles mark the area in proper motion space used for building the histograms of the parallaxes shown in Fig. 4. The red cross in the upper right edge of the plot shows median values [(0.101, 0.092) mas yr⁻¹] of the proper motion uncertainties for the stars selected as vdBH 99 members.